The present invention relates to an improvement in a combination of a windshield wiper and a windshield washer for washing off dust, dirt, the dead bodies of worms etc. on the surface of a windshield of a motor vehicle, and more particularly to a device for controlling the duration of ejecting a washer liquid onto the surface of the windshield in relation to the moving positions of wiper blades of the windshield wiper.
Motor vehicles such as automotive vehicles are in general provided with windshield wipers having wiper blades to wipe off rain and snow on a front windshield to obtain a wide field of view for a driver of the vehicle. Additionally, the vehicles are further equipped with windshield washers which are operated in cooperation with the windshield wipers to wash down dust, dirt, the dead bodies of various worms etc. adhering to the windshield of the vehicle.
A conventional windshield washer is so constructed that a washer liquid is continuously ejected onto the surface of the windshield as long as the driver continues to push a switch to operate the washer. However, such a windshield washer encounters the problem that the washer liquid which is being ejected from a nozzle strikes even momentarily against the oscillating wiper blade and accordingly the washer liquid is dispersed onto the surface of the windshield. This considerably narrows the field of view of the driver until the wiper blade wipes off the dispersed washer liquid on the windshield. Besides, the continuous ejection of the washer liquid causes a further problem in that there is a time period in which the washer liquid is ejected rearwardly of the the wiper blade in the moving direction of the wiper blade. The thus ejected washer liquid does not serve to wash off the windshield and flows down on the windshield, wasting the washer liquid.